1. Technical Field
The present invention relates to an image device adapted to simultaneously illuminate and image a imaging-object mounted on a table.
2. Related Art
An imaging device of this kind will typically be equipped with an illumination unit intended to be employed when the imaging-object which has been mounted on a table is being imaged by a camera of a camera head, in order augment the quantity of light during the imaging process. Such illumination units are encountered, for example, in Japanese Patent Laid-open Gazette 2003-209717 and Japanese Patent No. 3682285. Illumination units in conventional devices are furnished with a large number of low-luminance light-emitting diodes (LEDs) to provide uniform illumination over a wide area of the table, however, the use of such a large number of LEDs contributes to more complicated wiring schemes, as well as posing the problem of laborious maintenance.
Also, in imaging devices of this kind, the illumination unit is composed of light-emitting diodes (LEDs) arranged in a line at equal pitch, with the light of each LED being directed onto the table upper face to illuminate it.
However, where light is directed in the same way from each LED of an array of LEDs that have been arranged in a line at equal pitch, differences in brightness may arise between the table center area and areas to the sides thereof on the table upper face, and uneven brightness may occur in the area being imaged by the camera head as well. For this reason, in Japanese Patent No. 3682285, it is proposed to reduce uneven brightness by using an illumination unit that has large number of LEDs arrayed in a line along a prescribed length, and to carry out control whereby all of the LED are lit at once, as well as on/off control of LEDs according to the extent of uneven brightness.
However, as such on/off control of LEDs according to the extent of uneven brightness necessitates measurement of uneven brightness, the complexity of doing so must be pointed out. Moreover, while the complexity of control can be reduced by illuminating all of the LEDs at once, due to the need to arrange a large number of LEDs in a line along a prescribed length, problems were encountered in terms of an increased number of parts and higher power consumption.